
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
  "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" lang="zh">
  <head>
    <meta http-equiv="X-UA-Compatible" content="IE=Edge" />
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>Data marshalling support &#8212; Python 3.6.6rc1 文档</title>
    <link rel="stylesheet" href="../_static/pydoctheme.css" type="text/css" />
    <link rel="stylesheet" href="../_static/pygments.css" type="text/css" />
    <script type="text/javascript" src="../_static/documentation_options.js"></script>
    <script type="text/javascript" src="../_static/jquery.js"></script>
    <script type="text/javascript" src="../_static/underscore.js"></script>
    <script type="text/javascript" src="../_static/doctools.js"></script>
    <script type="text/javascript" src="../_static/sidebar.js"></script>
    <link rel="search" type="application/opensearchdescription+xml"
          title="在 Python 3.6.6rc1 文档 中搜索"
          href="../_static/opensearch.xml"/>
    <link rel="author" title="关于这些文档" href="../about.html" />
    <link rel="index" title="索引" href="../genindex.html" />
    <link rel="search" title="搜索" href="../search.html" />
    <link rel="copyright" title="Copyright" href="../copyright.html" />
    <link rel="next" title="Parsing arguments and building values" href="arg.html" />
    <link rel="prev" title="Importing Modules" href="import.html" />
    <link rel="shortcut icon" type="image/png" href="../_static/py.png" />
    <link rel="canonical" href="https://docs.python.org/3/c-api/marshal.html" />
    
    <script type="text/javascript" src="../_static/copybutton.js"></script>
    <script type="text/javascript" src="../_static/switchers.js"></script>
    
    
 

  </head><body>  
    <div class="related" role="navigation" aria-label="related navigation">
      <h3>导航</h3>
      <ul>
        <li class="right" style="margin-right: 10px">
          <a href="../genindex.html" title="General Index"
             accesskey="I">索引</a></li>
        <li class="right" >
          <a href="../py-modindex.html" title="Python 模块索引"
             >模块</a> |</li>
        <li class="right" >
          <a href="arg.html" title="Parsing arguments and building values"
             accesskey="N">下一页</a> |</li>
        <li class="right" >
          <a href="import.html" title="Importing Modules"
             accesskey="P">上一页</a> |</li>
        <li><img src="../_static/py.png" alt=""
                 style="vertical-align: middle; margin-top: -1px"/></li>
        <li><a href="https://www.python.org/">Python</a> &#187;</li>
        <li>
          <span class="language_switcher_placeholder">zh</span>
          <span class="version_switcher_placeholder">3.6.6rc1</span>
          <a href="../index.html">Documentation </a> &#187;
        </li>

          <li class="nav-item nav-item-1"><a href="index.html" >Python/C API Reference Manual</a> &#187;</li>
          <li class="nav-item nav-item-2"><a href="utilities.html" accesskey="U">Utilities</a> &#187;</li>
    <li class="right">
        

    <div class="inline-search" style="display: none" role="search">
        <form class="inline-search" action="../search.html" method="get">
          <input placeholder="Quick search" type="text" name="q" />
          <input type="submit" value="Go" />
          <input type="hidden" name="check_keywords" value="yes" />
          <input type="hidden" name="area" value="default" />
        </form>
    </div>
    <script type="text/javascript">$('.inline-search').show(0);</script>
         |
    </li>

      </ul>
    </div>    

    <div class="document">
      <div class="documentwrapper">
        <div class="bodywrapper">
          <div class="body" role="main">
            
  <div class="section" id="data-marshalling-support">
<span id="marshalling-utils"></span><h1>Data marshalling support<a class="headerlink" href="#data-marshalling-support" title="永久链接至标题">¶</a></h1>
<p>These routines allow C code to work with serialized objects using the same
data format as the <a class="reference internal" href="../library/marshal.html#module-marshal" title="marshal: Convert Python objects to streams of bytes and back (with different constraints)."><code class="xref py py-mod docutils literal notranslate"><span class="pre">marshal</span></code></a> module.  There are functions to write data
into the serialization format, and additional functions that can be used to
read the data back.  Files used to store marshalled data must be opened in
binary mode.</p>
<p>Numeric values are stored with the least significant byte first.</p>
<p>The module supports two versions of the data format: version 0 is the
historical version, version 1 shares interned strings in the file, and upon
unmarshalling.  Version 2 uses a binary format for floating point numbers.
<em>Py_MARSHAL_VERSION</em> indicates the current file format (currently 2).</p>
<dl class="function">
<dt id="c.PyMarshal_WriteLongToFile">
void <code class="descname">PyMarshal_WriteLongToFile</code><span class="sig-paren">(</span>long<em>&nbsp;value</em>, FILE<em>&nbsp;*file</em>, int<em>&nbsp;version</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMarshal_WriteLongToFile" title="永久链接至目标">¶</a></dt>
<dd><p>Marshal a <code class="xref c c-type docutils literal notranslate"><span class="pre">long</span></code> integer, <em>value</em>, to <em>file</em>.  This will only write
the least-significant 32 bits of <em>value</em>; regardless of the size of the
native <code class="xref c c-type docutils literal notranslate"><span class="pre">long</span></code> type.  <em>version</em> indicates the file format.</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMarshal_WriteObjectToFile">
void <code class="descname">PyMarshal_WriteObjectToFile</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em>&nbsp;*value</em>, FILE<em>&nbsp;*file</em>, int<em>&nbsp;version</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMarshal_WriteObjectToFile" title="永久链接至目标">¶</a></dt>
<dd><p>Marshal a Python object, <em>value</em>, to <em>file</em>.
<em>version</em> indicates the file format.</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMarshal_WriteObjectToString">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="descname">PyMarshal_WriteObjectToString</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em>&nbsp;*value</em>, int<em>&nbsp;version</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMarshal_WriteObjectToString" title="永久链接至目标">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p>Return a bytes object containing the marshalled representation of <em>value</em>.
<em>version</em> indicates the file format.</p>
</dd></dl>

<p>The following functions allow marshalled values to be read back in.</p>
<p>XXX What about error detection?  It appears that reading past the end of the
file will always result in a negative numeric value (where that's relevant),
but it's not clear that negative values won't be handled properly when there's
no error.  What's the right way to tell? Should only non-negative values be
written using these routines?</p>
<dl class="function">
<dt id="c.PyMarshal_ReadLongFromFile">
long <code class="descname">PyMarshal_ReadLongFromFile</code><span class="sig-paren">(</span>FILE<em>&nbsp;*file</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMarshal_ReadLongFromFile" title="永久链接至目标">¶</a></dt>
<dd><p>Return a C <code class="xref c c-type docutils literal notranslate"><span class="pre">long</span></code> from the data stream in a <code class="xref c c-type docutils literal notranslate"><span class="pre">FILE*</span></code> opened
for reading.  Only a 32-bit value can be read in using this function,
regardless of the native size of <code class="xref c c-type docutils literal notranslate"><span class="pre">long</span></code>.</p>
<p>On error, raise an exception and return <code class="docutils literal notranslate"><span class="pre">-1</span></code>.</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMarshal_ReadShortFromFile">
int <code class="descname">PyMarshal_ReadShortFromFile</code><span class="sig-paren">(</span>FILE<em>&nbsp;*file</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMarshal_ReadShortFromFile" title="永久链接至目标">¶</a></dt>
<dd><p>Return a C <code class="xref c c-type docutils literal notranslate"><span class="pre">short</span></code> from the data stream in a <code class="xref c c-type docutils literal notranslate"><span class="pre">FILE*</span></code> opened
for reading.  Only a 16-bit value can be read in using this function,
regardless of the native size of <code class="xref c c-type docutils literal notranslate"><span class="pre">short</span></code>.</p>
<p>On error, raise an exception and return <code class="docutils literal notranslate"><span class="pre">-1</span></code>.</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMarshal_ReadObjectFromFile">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="descname">PyMarshal_ReadObjectFromFile</code><span class="sig-paren">(</span>FILE<em>&nbsp;*file</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMarshal_ReadObjectFromFile" title="永久链接至目标">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p>Return a Python object from the data stream in a <code class="xref c c-type docutils literal notranslate"><span class="pre">FILE*</span></code> opened for
reading.</p>
<p>On error, sets the appropriate exception (<a class="reference internal" href="../library/exceptions.html#EOFError" title="EOFError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">EOFError</span></code></a> or
<a class="reference internal" href="../library/exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a>) and returns <em>NULL</em>.</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMarshal_ReadLastObjectFromFile">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="descname">PyMarshal_ReadLastObjectFromFile</code><span class="sig-paren">(</span>FILE<em>&nbsp;*file</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMarshal_ReadLastObjectFromFile" title="永久链接至目标">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p>Return a Python object from the data stream in a <code class="xref c c-type docutils literal notranslate"><span class="pre">FILE*</span></code> opened for
reading.  Unlike <a class="reference internal" href="#c.PyMarshal_ReadObjectFromFile" title="PyMarshal_ReadObjectFromFile"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyMarshal_ReadObjectFromFile()</span></code></a>, this function
assumes that no further objects will be read from the file, allowing it to
aggressively load file data into memory so that the de-serialization can
operate from data in memory rather than reading a byte at a time from the
file.  Only use these variant if you are certain that you won't be reading
anything else from the file.</p>
<p>On error, sets the appropriate exception (<a class="reference internal" href="../library/exceptions.html#EOFError" title="EOFError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">EOFError</span></code></a> or
<a class="reference internal" href="../library/exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a>) and returns <em>NULL</em>.</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMarshal_ReadObjectFromString">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="descname">PyMarshal_ReadObjectFromString</code><span class="sig-paren">(</span>const char<em>&nbsp;*data</em>, Py_ssize_t<em>&nbsp;len</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMarshal_ReadObjectFromString" title="永久链接至目标">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p>Return a Python object from the data stream in a byte buffer
containing <em>len</em> bytes pointed to by <em>data</em>.</p>
<p>On error, sets the appropriate exception (<a class="reference internal" href="../library/exceptions.html#EOFError" title="EOFError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">EOFError</span></code></a> or
<a class="reference internal" href="../library/exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a>) and returns <em>NULL</em>.</p>
</dd></dl>

</div>


          </div>
        </div>
      </div>
      <div class="sphinxsidebar" role="navigation" aria-label="main navigation">
        <div class="sphinxsidebarwrapper">
  <h4>上一个主题</h4>
  <p class="topless"><a href="import.html"
                        title="上一章">Importing Modules</a></p>
  <h4>下一个主题</h4>
  <p class="topless"><a href="arg.html"
                        title="下一章">Parsing arguments and building values</a></p>
  <div role="note" aria-label="source link">
    <h3>This Page</h3>
    <ul class="this-page-menu">
      <li><a href="../bugs.html">Report a Bug</a></li>
      <li>
        <a href="https://github.com/python/cpython/blob/3.6/Doc/c-api/marshal.rst"
            rel="nofollow">Show Source
        </a>
      </li>
    </ul>
  </div>
        </div>
      </div>
      <div class="clearer"></div>
    </div>  
    <div class="related" role="navigation" aria-label="related navigation">
      <h3>导航</h3>
      <ul>
        <li class="right" style="margin-right: 10px">
          <a href="../genindex.html" title="General Index"
             >索引</a></li>
        <li class="right" >
          <a href="../py-modindex.html" title="Python 模块索引"
             >模块</a> |</li>
        <li class="right" >
          <a href="arg.html" title="Parsing arguments and building values"
             >下一页</a> |</li>
        <li class="right" >
          <a href="import.html" title="Importing Modules"
             >上一页</a> |</li>
        <li><img src="../_static/py.png" alt=""
                 style="vertical-align: middle; margin-top: -1px"/></li>
        <li><a href="https://www.python.org/">Python</a> &#187;</li>
        <li>
          <span class="language_switcher_placeholder">zh</span>
          <span class="version_switcher_placeholder">3.6.6rc1</span>
          <a href="../index.html">Documentation </a> &#187;
        </li>

          <li class="nav-item nav-item-1"><a href="index.html" >Python/C API Reference Manual</a> &#187;</li>
          <li class="nav-item nav-item-2"><a href="utilities.html" >Utilities</a> &#187;</li>
    <li class="right">
        

    <div class="inline-search" style="display: none" role="search">
        <form class="inline-search" action="../search.html" method="get">
          <input placeholder="Quick search" type="text" name="q" />
          <input type="submit" value="Go" />
          <input type="hidden" name="check_keywords" value="yes" />
          <input type="hidden" name="area" value="default" />
        </form>
    </div>
    <script type="text/javascript">$('.inline-search').show(0);</script>
         |
    </li>

      </ul>
    </div>  
    <div class="footer">
    &copy; <a href="../copyright.html">Copyright</a> 2001-2018, Python Software Foundation.
    <br />
    The Python Software Foundation is a non-profit corporation.
    <a href="https://www.python.org/psf/donations/">Please donate.</a>
    <br />
    Last updated on 6月 24, 2018.
    <a href="../bugs.html">Found a bug</a>?
    <br />
    Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 1.7.2.
    </div>

  </body>
</html>